1. Field of the Invention
The invention relates generally to photographic apparatus, and more particularly to a synchronizing mechanism for flash firing and shutter operation in a camera.
2. Description of the Prior Art
It is well known in the photographic arts to fire a flash lamp by means of an electrical pulse generated by a piezoelectric crystal and to provide a mechanism for synchronizing such flash firing with the shutter operation of a camera. For the most part, known synchronizing mechanisms for flash firing and shutter operation have tended to be mechanically complex. For example, as disclosed in U.S. Pat. No. 3,697,142, granted June 6, 1975, a firing spring is unlatched to cause a hammer on the spring to strike a piezoelectric crystal, activating the crystal to generate an electrical pulse for flash firing. In timed relationship, a high energy lever is unlatched to actuate a shutter blade for initiating a film exposure. The shutter begins to open after the piezoelectric crystal is struck, to allow for the inherent delay between striking the crystal and peak illumination of the flash. Full opening of the shutter is reached substantially concurrent with peak illumination. While such a synchronizing mechanism has been generally accepted, the use of separate devices for activating the piezoelectric crystal and for operating the shutter gives rise to reliability problems and increases the manufacturing and assembly costs of a camera.
Other known, less complex, mechanisms for synchronizing flash firing and shutter operation can have different problems. For example, in U.S. Pat. No. 3,677,153, granted July 18, 1976, although simplification is achieved by using the shutter blade as a hammer for striking the piezoelectric crystal, the blade strikes the crystal after uncovering the exposure aperture. Consequently, there is no coincidence between peak illumination of the flash and full opening of the shutter. Instead, peak illumination is reached as the blade re-covers the aperture. Another problem may arise from camera shake caused by the impact of the blade against the crystal. Since this shake occurs before the blade re-covers the aperture, the film image of the object being photographed may be smeared, causing an attendant loss of resolution in a developed print.
Another simplified syncrhonizing mechanism, in Ger. Ols. No. 2,021,401, published Nov. 11, 1971, includes a striker arm and a shutter actuating arm which are held in respective adjacent cocked positions by a common latch. When simultaneously released, the arms are urged by separate springs to strike the piezoelectric generator and a shutter blade. Although this design is simplified by the use of a common latch, it requires separate arms and springs, which may cause variations in the timed relationship between flash firing and shutter operation from camera to camera, especially in mass production.